Question

a random sample of 160 households is selected to estimate the mean amount spent on electric service. a 95% confidence interval was determined from the sample results to be ($151, $216). which of the following is the correct interpretation of this interval? a. there is a 95% chance that the mean amount spent on electric service is between $151 and $216. b. we are 95% confident that the mean amount spent on electric service among all households is between $151 and $216. c. 95% of the households will have an electric bill between $151 and $216. d. we are 95% confident that the mean amount spent on electric service among the 160 households is between $151 and $216.

Explanation:

A confidence interval is used to estimate a population parameter. Here, the population is all households. A 95% confidence interval means that if we were to take many samples and construct confidence intervals in the same way, about 95% of them would contain the true population mean. We are 95% confident that the true mean amount spent on electric service among all households lies within the calculated interval.

Answer:

B. We are 95% confident that the mean amount spent on electric service among all households is between $151 and $216.